Magnetic coupler



J. N. BEEBE MAGNETIIC COUPLER 1 Dec. 30, 1952 2 SHEETS-SHEET 2 FiledMarch 5, 1948 MVENTOR BIO/IN M 5:50: W

Patented Dec. 30, 1952 UNITED STATES RATENT OFFICE MAGNETIC COUPLER JohnN. Beebe, Newton, Mass., assignor to Raytheon Manufacturing Company, acorporation of Delaware Application March 5, 1948, Serial No. 13,312

3 Claims. I

This invention relates in general to cable connectors for alternatingelectric power cables and more particularly to a novel magnetic couplerfor connecting together portions of such a cable in readilydis'con'nectible fashion.

It is the principal object of this invention to provide a readilydisconnectible cable connector for alternating electric power cableswhich is completely suitable in all respects for use aboard barges andthe like which carry inflammable products, such as petroleum products.

It is accordingly an object of the invention to provide a readilydisconnectible cable connector for alternating electric power cableswherein there is no sparking when connection ismade or broken.

It is another object to provide such a connector that provides inductiveor magnetic coupling to a uniform degree without critical manufacturingtolerances.

It is another object to provide such a connector wherein the electricalfunction is compietely unaffected by immersion in water.

It is a further objectto provide such a conne'ctor wherein allelectrical connections to power cables are fully shielded from water.

It is a still further object to provide such a connector that is ri idlysheathed and protected from harm due to shocks, banging, dropping, orcompression under heavy weights, and in which each separable partthereof is individual- 1y so protected.

It is another object to provide such a connector that remains coupledtogether when so placed, and does not come apart when kicked, steppedon, or otherwise treated in the course of its normal useage, but whichreadily becomes disconnected when a force of greater than apredetermined amount is applied to separate its parts.

Other and further objects and features of the invention will becomeapparent from the de-' scription of a particular embodiment thereof thatfollows. The description refers to the accompanying drawings, whereinFig. 1 shows a barge tow employing the invention; b

Fig. 2 is an enlarged view of the abutting ends of two of the bargesshown in Fig. 1;

Fig. 3 is a side elevation of Fig. 2

Fig. 4 is a longitudinal sectional view of a connector in accordancewith the invention;

Fig. 5 is a section along line 5-5 in Fig. 4; I

Fig. 6 is an enlarged view of the retaining arrangement employed in theconnector of Fig. 4;

Fig. 7 shows the connector when the two parts thereof are connectedtogether; and

Fig. 8 shows the connector with the two parts thereof separated.

Referring now to Figs. 1, 2 and 3, Fig. 1 shows an arrangement known asa barge tow. A plurality of freight barges H], H, [2, etc., are firmlyfastened together as shown most clearly in Fig. 3 by means of stanchionsi3 mounted one at each corner of each barge, and lines l4 looped overthe stanchions to tie the barges together. The lines are crosseddiagonally and are provided with turnbuckles [5 for tightening. Thebarges thusform a rigid unitary vessel about 800 or 1006 feet long. Thisvessel is pushed by a powered craft It, which is fastened firmly to oneof the end bar es, here, barge l2. The powered craft [6 is provided witha pilot house ii and a rudder l8. Screws are, of course, also provided,but are not illustrated.

For various purposes, it is desired to convey electric signals and powerbetween the pilot house and the forward barges, and to this end a powercable 2:] is laid on the decks of the barges, from one barge to thenext. Because various ones of the barges are separated from the tow andother barges may be added at various docking points, in the same manneras freight cars are attached to and taken from freight trains, thiscable 28 is provided with connectors 2i at each junction between barges,whereby the cable may be readily broken and made up.

Additional stanchions 22 are provided on each barge at the corners onone side only thereof. Each cable connector 2| is made of two separableparts 23 and 24 as shown more clearly in Figs. '7 and 8, and each partis connected by way of a chain 25, for example, to one of the additionalstanchions 22. As will be described in detail below,- the power cable 20is brought into and out of the connector parts 23 and 24, and theconnector remains assembled until pulled apart intentionally or becauseof a break in the tow. The chains 25 are long enough to permit a smalldegree of play and sidesway in the position of the connector 2 I, butare sufficiently short so that, when the connector is parted, neitherpart 23 nor 24 can fall over the side of the barge, where it might becrushed between barges, or between the barge and a dock. In addition,the cable 29 is left sufliciently loose at the connector so that, if twobarges part, the chains 25 will become tight before the cable does, andpart the connector 2i before the cable pulls out of either part 23 or 24thereof.

Because the barges very often carry inflam mable products, the connectoris spark free, and, because it is roughly handled, there is a rigidsheath provided and the parts are individually waterproofed, all as willbe described below.

The stanchions 22 that support the connectors 2! are sufficiently high,and the chains 25 sufficiently long, so that there can be some play orfreedom of motion before the connector is pulled apart, but, when it ispulled apart, as illustrated by dotted lines in Fig. 3, neither part ofit will fall over the side of the barge. In this way the crushing of thepart between barges or barge and dock is avoided, while the connector isin a con venient position for handling.

The cable 23 carries power from a control station 26 in the pilot houseii to a forward station 21. The two stations 23 and 21 may, for example,be telephone stations, or they may be, respec tively, the locations of adepth-finder indicator andan electroacoustic transducer, in which case asignal having a frequency of to 50 kc./sec. may be transmitted throughthe cable In any case, the cable 23 will carry alternating current, aswill appear from the discussion to follow.

Referring now to Figs. 4 to 8, inclusive, it will be seen that theconnector 2! comprises essentially a magnetic coupler in two separableparts, each of which is provided with a rigid protecting sheath and hasits electrical parts all protected from water, and that the magneticcoupler portions and the sheaths all interfit telescopically when theconnector is assembled. Thus the first part 23 of the connector isprovided with a first coil 31 which is wound on a coil form 32.Contained within the coil form 32 is a magnetizable core 33, which, forhigh frequencies of the order of 40 to 50 kilocycles per second, ispreferably of powdered iron. Surrounding the first coil 3% is awaterproof covering or tube 34, which may, for example, be coil formmaterial coated with beeswax or a waterproof varnish. The end ofthistube 3c is closed with a waterproof closure in the form of a disc35. The coil form 32 and the tube 34 are both made of insulatingmaterial, and are mounted on an insulating base 35, being cemented intogrooves cut therein. The outer covering tube 34 at least must be sealedto the base 36 in watertight fashion. Two holes 33 are provided acrossthe base 33, starting from points between the grooves for the coil form32 and tube 34, for the passage of wires from the coil 3| through thebase.

The base 36 is mounted in a rigid sheath 38, which may be a piece ofmetal tube or pipe for strength, and is preferably of brass to avoid thestriking of sparks between the connector and steel parts of the barges.The base is provided with a peripheral groove 39 wherein is fitted arubber or similar ring 43 to provide a water seal between the base andthe sheath 38. The base is firmly held in place in the sheath by meansof screws 4!, placed on the side of the groove 39 that is toward thefree end of the coil assembly.

The sheath 38 is closed at the end holding the base 33 by a rigid endcap 42 which has a cavity opening toward the base 33 and forming withthe base a chamber 43 for wire connections and certain electricalcomponents to be described later. The closure between the shield 38 andthe end cap 42 is made rigid and watertight, as by brazing, when brassis used, or another suitable process. The far end of the end cap isprovided with an opening 44 for the passage of the cable 23, and a softgasket 45 of rubber or the like is placed around the cable in theopening. A pressure cap 41 fits around the cable and has a boss 48extending and fitting into the opening 44. The pressure cap is attachedto the end cap by a plurality of bolts 49, which, when tightened, causethe boss 48 to apply axial pressure to the gasket 45 so that it isenlarged in radial directions and is squeezed tightly into the opening44 and against the cable 20. The cable is thereby compressed and firmlyheld in the opening 44, and the passage is made watertight.

The gasket 45 and the ring 45 thus cooperate to maintain the chamber 43watertight, so that the electrical connections therein are always dry.The connections that are made in this chamber are shown in Fig. 5. Wires5! and 52, which are the leads from the coil 3|, emerge from the holes31 in the base 36. Three binding posts 53, 54 and 55 and a capacitor 56are mounted on the base 35 on the side facing into the chamber 43. Thecapacitor 56 is connected across two binding posts 54 and 55, and onecoil lead 52 is connected to one of these, here 54. The other coil lead5| is connected to the third binding post 53. The cable 20 may then beconnected to binding posts 53 and 55, in which case the capacitor 56 isin series with the coil 3 I. The connection may be made otherwise ifdesired.

The second part 24 of the connector is provided with a second coil 6|which is wound on a coil form 62 having an inner diameter slightlylarger than the outer diameter of the outer watertight tube 34 thatprotects the first coil 3 I, so that the two coils may be telescopicallyfitted together. Surrounding the second coil 5| is a second tube 63, ofwaterproof material like tube 34. The second coil form 32 andwater-protective tube 63 are both supported in a waterproof andnon-conductive base 64 in concentric grooves cut therein and cemented infirmly and with a watertight seal, as is done in the first part 23 ofthe connector. A front block 65, of annular form and having about thesame outside diameter as the base 64, is similarly fastened to the otherend of the second coil form and protective tube assembly. Lead wireholes 65 are provided in the base 64 between the two tubes as in thebase 36 of the first part.

The second coil assembly fits snugly into and is protected by a rigidprotective sheath 68, like the first part sheath 3B but of smallerdiameter so that it can be telescopically fitted thereinto. This sheath68 has a rigid annular front end piece 69, attached thereto as, forexample, by brazing, and the second coil assembly is fitted into itssheath with the front block 65 close to or in contact with this endpiece. In this manner the second coil assembly is adequately protectedfrom shock and concussion at the front and sides. The front block 65 isprovided with a circumferential groove H and a ring gasket 12 thereinlike the ring 40, which provides a watertight seal at this end of theassembly. The second coil assembly with the protective sheath 68 thusfits over the first part coil assembly including the watertight tube 34and into the first part protective sheath 38.

The second part 24 is provided with an end cap 15 which is recessed inone end and has portions of successively reduced outer diameter Itand11, respectively, toward the recessed end. The portion 11 of smallestouter diameter fits into the back end of the sheath 68. This portion isprovided exteriorly with an annular groove 18 and a ring gasket 19therein like rings 40 and 72, to

provide a watertight seal between the end cap 15 and the sheath 68.Screws 8| hold the sheath 68 and the end cap firmly together. Theperiphery of the open end of the end cap abuts the end block 64, beingproperly positioned with respect thereto by means of a. locating pin 82,and a chamber 83 is thus provided with the end block 64 as one wallthereof. This chamber has in the opposite wall an opening 84 with anannular gasket 85 therein, through which the other part of the cable 29passes. A pressure cap 86 and bolts 81 are employed to hold the cablefirmly in place and effect a watertight seal, all in the same manner asis done in the first part 23 of the connector. In fact, the pressurecaps 36 and 41 are identical.

Inside the chamber 83, the lead wires 9| and 92 from the second coil 6!are brought to lugs 93 and 94, respectively, mounted on the base 64, andthe cable 29 is connected to these lugs.

In each chamber the cable may be taped at the end to assist inpreventing play and pulling out.

The end cap 15 has in its intermediate portion of reduced diameter 19 aseries of ball-retainers 96 for holding the two parts 23 and 24 of theconnector together in a readily releasable fashion. One of these isshown enlarged in Fig. 6. Each retainer includes a metal sphere 96 whichis held in place in a hole 9! in the end cap 15, by means of a flange99. A spring 99 urges the sphere 99 outward. A'cooperating hole ordetent IOI in the first part sheath 38 admits a portion of the sphere 96when the twoparts of the connector are assembled, and the sphere thenserves to hold the two parts in assembled relation. A pull ofpredetermined force, suitably about 25 pounds, is sufficient to pull thetwo parts 23 and 24 apart against the retaining action of the spheres 96in holes NH. The retainers are made by first drilling the hole 91 oflarger diameter than the sphere 96, inserting first the spring 99 andthen the sphere 96, and hammering out the flange 98 over the sphere, aswith a sharp tool.

Each of the pressure caps 4'! and 86 is provided with a tie ring I94,I95, respectively, by which the two parts of the connector are tied orlinked to the chains 25. As stated above, the pressure caps areidentical, and the tie rings are cast or formed integral therewith.

The construction that has just been described i designed not only toprovide rigidity, waterproofness, spark-free operation, generalruggedness, and other advantages thus far apparent, but also to makepossible inexpensive and easy assembly. Considering the first part 23,this part is assembled as follows. The sheath 33 and end cap 42 arefirst assembled. These parts may be fabricated in one piece if desired,but it will be less expensive to fabricate them as described herein. Thecoil assembly, including the base 36 with its water-seal ring 49 and thecapacitor 56 and binding posts or lugs 53, 54 and 55, is made up as aseparate unit. The pressure cap 41 and gasket 45 are then put loosely inplace on the cable 29, which is then inserted through the hole 44 anddrawn out the open end of the sheath 33, where connection to the lugs 53and 55 is made. The coil assembly is then inserted in the sheath 38, thecable 29 being suitably withdrawn through the hole 44 until the base 36is in the proper position and the screws 4| can be put in place. Thegasket 45 is then seated in the opening 44 and the pressure cap 4'! isput in place and the bolts 49 are tightened evenly all around.

The assembly of the second part 24 is equally simple. The second coilassembly, including the base 94 with lugs 93 and 94 thereon and thefront block 65 with the water-seal ring 12 in place thereon, isassembled as a saparate unit. The sheath 68 and front end piece 69 areassembled as a unit, which may be stamped or otherwise formed, orassembled from two separate pieces as described herein. The coilassembly is then inserted in the sheath with the front block 65 flushwith or very close to the front end piece 69. The pressure cap 86,gasket 35, and end cap 55 are then loosely fitted over the cable 29,which is then connected to the lugs 93 and 94. The end cap I5 has on itthe water-seal ring ".9 and carries the retainer spheres 96. The end capis then inserted in the sheath 69, the joint being made watertight bythe ring 19, and the screws Bl are driven in. The gasket and pressurecap 86 are then assembled and the bolts 8'!" are tightened in place. Theconnector is now ready for use. The two parts appear as shown in Fig. 8and the assembled connector appears as shown in Fig. '7.

When the connector is assembled, the two coils 3i and 8! and the core 33function as an open-core transformer. This transformer has a certainamount of leakage reactance, which is tuned out at the operatingfrequency with the capacitor 56. Where the cable 29 is carrying a bandof frequencies, for example, from 40 kc. to 50 kc., the capacitor 56 ischosen to tune out the leakage reactance at 45 kc. With a low Q, thisprovides a sufficiently broad band for frequencies in this entire range.Because of the elongated construction of the transformer, the exactdegree of telescopic interfitting is not critical so far as variationsin leakage reactance and magnetic coupling is concerned. That is, therere no highly precise tolerances to be met in the positioning of theretainer spheres 96, the holes 16!, or any of the other sizes. Ordinarytolerances are satisfactory. Also, because of the radial symmetry of thetwo parts, there is no critical assembly consideration. The two partsare merely interfitted as described herein and snapped together. Theentire device is foolproof and simple.

Since many changes in particular details of the embodiment of theinvention shown and described herein may be made without departing fromthe spirit of the invention, it is intended that the appended claimsshall not be limited to particular details shown and described, butshall be limited only by the prior art.

Having now described my invention, I claim:

1. A spark-free and watertight disconnectible cable connector foralternating electric power cables comprising two separate parts adaptedto be fitted telescopically together, each part comprising asubstantially rigid sheath open at one end and having a watertightchamber at the other end, said sheaths being adapted to fit onetelescopically over the other when brought together with their open endsconfronting, a pair of elongated transformer windings mounted axiallyone within each of said sheaths and adapted to fit telescopically onewithin the other and both within both of said sheaths when said sheathsare fitted together, means within the watertight chambers of each ofsaid parts for making electrical connections to the coil mounted in saidpart, a first wire passage through the closed end of each part, a clampmember fastened to each closed end, said clamp member having a secondwire passage in register with the first wire passage, and a flexiblecompression ring between each closed end and its clamp member, said ringadapted when under compression frictionally engage a wire in saidpassages.

2. A spark-free and watertight disconnectible cable connector foralternating electric power cables comprising two separate parts adaptedto be fitted telescopically together, each part comprising asubstantially rigid sheath open at one end, said sheaths being adaptedto fit one telescopically over the other when brought together withtheir open ends confronting, a pair of elongated transformer windingsmounted axially one Within each of said sheaths and adapted tofittelescopically one within the other and both within both of said sheathswhen said sheaths are fitted together, a first wire passage through theclosed end of each part, a clamp member fastened to each closed end,said clamp member having a second wire passage in register with thefirst wire passagaiand a flexible compression ring between each closedend and its clamp member, said ring adapted when under compressionfrictionally to engage a wire in said passages.

3. A spark-free and watertight disconnectible cable connector foralternating electric power cables comprising two separate parts adaptedto be fitted'telescopically together, each part comprising asubstantially rigid sheath open at one end, said sheaths being adaptedto fit one telescopically over the other when brought together withtheir open ends confronting, a pair of elon- 30 gated transformerwindings mounted axially one within each of said sheaths and adapted tofit 8 telescopically one within the other and both within both of saidsheaths when said sheaths are fitted together, means for yieldablyholding said connector in its assembled relation when the parts are sointerfitted, a first wire passage through the closed end of each part, aclamp member fastened to each closed end, said clamp member having asecond wire passage in register with the first wire passage, and aflexible compression ring between each closed end and its clamp member,said ring adapted when under compression frictionally to engage a wirein said passages.

JOHN N. BEEBE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,462,572 Grabell July 24, 19231,499,686 Northrop July 1, 1924 2,055,369 Warren Sept. 22, 19362,058,037 Rigandi Oct. 20, 1936 2,130,432 Schmook Sept. 20, 19382,379,664 Stanko July 3, 1945 2,483,815 Easton Oct. 4, 1949 OTHERREFERENCES Cannon Plugs, Cannon Electric Development Company, September1943, page 3.

